Water-Based Adhesives

ABSTRACT

An adhesive includes a polymeric latex, a penetrant selected from the group consisting of: terpenes, polylimonene, limonene, carvone, a-pinene, citral, dipentene, 1,8-cineole, eucalyptol, citronellol, geraniol, citronellene, terpinen-4-ol, borneol, camphor, guayule resin, and combinations thereof; and a reinforcing filler. The adhesive has a solids content of 35-65% and a pH of 9 to 12. Articles of manufacture, such as tires and air springs incorporate the adhesive to join rubber interfaces. A method of making the adhesive is also is provided.

FIELD

This disclosure relates to adhesives, particularly water-based adhesivesfor rubber compositions in the tire and air spring industry.

BACKGROUND

Articles made from connected rubber components may be joined togetherwith adhesive. In some applications, adhesives may be the primary optionfor joining components, particularly when mechanical methods such asstitching are not available, such as in articles that function as air ormoisture barriers. For example, rubber air springs and tires includeseparate rubber components that are joined with adhesives. Retread tiresalso may employ adhesive to join the new tread to the carcass, or toadhere an intermediate cushion layer to a carcass and/or a tread.

While two similar rubber components can be joined and then cured at thesame time and obtain a strong bond at the joint, this method of joiningrubber components is not preferable for some manufacturing processeswhere it is desirable to join the components and store them and/or allowthem to cure slowly. Rubber adhesives may be used to provide tack to arubber component while a rubber article is cured or stored.

SUMMARY

In an embodiment, an adhesive includes a polymeric latex, a penetrantselected from the group consisting of: terpenes, polylimonene, limonene,carvone, α-pinene, citral, dipentene, 1,8-cineole, eucalyptol,citronellol, geraniol, citronellene, terpinen-4-ol, borneol, camphor,guayule resin, and combinations thereof; and a reinforcing filler. Theadhesive has a solids content of about 35 to about 65% and a pH of about9 to 12.

In an embodiment, an article of manufacture includes an elastomericrubber component comprising an elastomer selected from the groupconsisting of: polychloroprene, butyl rubber, hevea and non-heveaderived natural rubber, polyisoprene, polybutadiene, nitrile rubber,poly(styrene-butadiene), and combinations thereof. The elastomericrubber component is joined at an interface with a second rubbercomponent or another portion of the elastomeric rubber component. Theinterface includes a layer of adhesive, which comprises: a polymericlatex; a penetrant selected from the group consisting of: terpenes,polylimonene, limonene, carvone, α-pinene, citral, dipentene,1,8-cineole, eucalyptol, citronellol, geraniol, citronellene,terpinen-4-ol, borneol, camphor, guayule resin, and combinationsthereof; and a reinforcing filler.

In an embodiment, a method includes the steps of: mixing together anadhesive composition comprising: a polymeric latex; a penetrant selectedfrom the group consisting of: terpenes, polylimonene, limonene, carvone,α-pinene, citral, dipentene, 1,8-cineole, eucalyptol, citronellol,geraniol, citronellene, terpinen-4-ol, borneol, camphor, guayule resin,and combinations thereof; and a reinforcing filler.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-sectional view of an embodiment of an airspring.

FIG. 2 is a cross-sectional view of a portion of an embodiment of atire.

FIG. 3 is a cross-sectional view of a portion of an embodiment of aretreaded tire.

DETAILED DESCRIPTION

U.S. provisional application 61/567,701, titled “Water-Based Adhesive,”filed on Dec. 7, 2011 and U.S. provisional application 61/606,161,titled “Water-Based Adhesive Including Guayule Extract,” filed on Mar.2, 2012 are incorporated herein by reference for all purposes.

Disclosed herein is a water-based, low VOC, latex adhesive for joiningrubber interfaces. The adhesive may be useful in a variety ofapplications. Particular examples of applications include those thatrequire strong rubber-to-rubber joints and that are utilized to providean air barrier, such as air springs and tire components. Application ofnew tread to retreaded tires is another application where thecomposition described herein may have particular utility.

In an embodiment the adhesive includes the following components: anaqueous polymeric latex, a penetrant, a reinforcing filler, a tackifier,and a stabilizer. In another embodiment, either the penetrant or thestabilizer or both may be omitted.

In an embodiment, the polymeric latex of the adhesive may be an aqueousemulsion of elastomers such as hevea and non-hevea (including guayule)natural rubber, polyisoprene, poly(styrene-butadiene),poly(isoprene-styrene), poly(isoprene-butadiene), polybutadiene,polychloroprene, nitrile rubber, butyl rubber, and combinations thereof.

In an embodiment, the polymeric portion of the latex may have a weightaverage molecular weight (Mw) of about 100,000 to about 30,000,000g/mol, such as about 100,000 to about 10,000,000 g/mol or about 100,000to about 5,000,000 g/mol and a number average molecular weight (Mn) ofabout 100,000 to about 30,000,000 g/mol, such as about 100,000 to about10,000,000 g/mol or about 100,000 to about 5,000,000 g/mol. The polymerportion may have a Tg of about −110° C. to about 10° C., such as about−110° C. to about −10° C. or about −110° C. to about −25° C.

In an embodiment, the polymeric latex may have a solids content of about10% to about 90%, such as about 20% to about 80%, or about 30% to about70%. The pH of the polymeric latex may be about 7 to about 14, such asabout 8 to about 13 or about 9 to about 12.

Without being bound to theory, when the adhesive is applied to anelastomer substrate, the penetrant component operates to open up theinterstices of the polymeric matrix of the elastomer it is applied to.This allows the adhesive composition to have better penetration andintermingling with the substrate elastomer. The surface area of theinterface between the adhesive and the elastomer substrate is alsoincreased.

In an embodiment, the penetrant is selected from terpenes, such aspolylimonene, limonene, α-pinene, dipentene, citronellene; or from thegroup consisting of carvone, citral, 1,8-cineole, eucalyptol,citronellol, geraniol, terpinen-4-ol, borneol, camphor, and combinationsthereof. In certain embodiments the penentrant is substantially orcompletely free of VOCs.

In another embodiment, the penetrant is guayule resin. As used herein,“guayule resin” means the naturally occurring non-rubber chemicalentities present in guayule shrub matter. These chemical entitiesinclude, but are not limited to, resins (such as terpenes), fatty acids,proteins, and inorganic materials, and include both polar and non-polarmoieties. Guayule resin can result from the isolation of rubber fromguayule shrub using organic solvent based processes. The resinrepresents the dried fraction (i.e., solvent removed) of materialisolated in the polar organic solvent phase from such a process.

In an embodiment, the guayule resin can be added as guayule rubberlatex, such latex including both the guayule rubber and the guayuleresin for use as the penetrant. In this embodiment, two components ofthe adhesive may be fulfilled by one source material. In anotherembodiment, purified guayule latex comprising 5% or less, alternatively3% or less, or 1% or less guayule resin may be used in the adhesivecomposition. In this embodiment, the penetrant is added separately, andmay include guayule resin.

The reinforcing filler component provides improved strength anddurability to the adhesive composition. This is in contrast to manyadhesives that use no or very little reinforcing filler. For example,some adhesive manufacturers may use carbon black in very small amountsto tint the adhesive, but not in reinforcing amounts.

In an embodiment, the reinforcing filler is carbon black, such asreinforcing grade carbon black. Examples include carbon black in theN100, N200, and N300 series. In some embodiments, a higher surface areacarbon black may provide improved performance. For example, the carbonblack may have an N₂SA surface area of about 10 to about 150 m²/g, suchas about 20 to about 140 m²/g or about 30 to about 130 m²/g. In someembodiments, an aqueous carbon black dispersion may be used. Preferably,the dispersion contains carbon black in an amount from about 20% toabout 50% by weight of the dispersion and the dispersion has a pH fromabout 7 to about 12. The particle size of the carbon black used in suchdispersions is preferably from about 10 to about 150 m²/g. Aqueouscarbon black dispersions which may be employed include, for example,AQUABLAK 5101, which is available from Solution Dispersions, andincludes a N100 series carbon black with 40% solids and pH of 10-1, andis stabilized with anionic and non-ionic surfactants.

The reinforcing fillers may be present in the adhesive in an amount ofabout 10 to about 80 phr (“per hundred rubber” is a by weight measure,and is based on the weight of the polymer in the polymeric latex set to100), for example, about 15 to about 60 phr, or about 20 to about 40phr.

The tackifier provides improved tack to the adhesive. Tackifiers thatmay be employed include, for example, TACOLYN 5003, TACOLYN 5070, orAQUATAC 6025. TACOLYN 5003 and 5070 are from EASTMAN CHEMICAL COMPANY,and they are aliphatic hydrocarbon resin tackifiers with a softeningpoint of 70-130° C. and a solids content of 45-50%. AQUATAC 6025 is fromARIZONA CHEMICAL, Co., and has a softening point of 26° C. and a solidscontent of 59-63%.

In an embodiment, the tackifier may be present in an amount of about 5to about 40 phr, such as about 10 to about 35 phr, or about 15 to about30 phr. In an embodiment, the tackifier has a pH of about 2 to about 13,such as about 3 to about 12, or about 4 to about 11 and a solids contentof about 30 to about 80%, such as about 35 to about 75%, or about 40 toabout 70%. In an embodiment, the tackifier has a softening point ofabout 5 to about 170° C., such as about 15 to about 150° C., or about 25to about 130° C.

The stabilizer component aids in keeping the composition in a latexemulsion state. An example class of stabilizers is non-ionicsurfactants, such as IGEPAL CO-887, which is a non-ionic surfactant fromRhodia Group. IGEPAL CO-887 is a nonylphenoxy poly(ethyleneoxy)ethanolsurfactant stabilizer with a 70% solids content. Other examples ofstabilizers that may be used in embodiments of the adhesive compositioninclude: PLURONIC F-68 from BASF, probenecid(4-(dipropylsulfamoyl)benzoic acid), tetraethyl orthosilicate, TWEEN 80,and acryloamido-2-methyl-1-propanesulfonic acid. The stabilizer may alsobe present in the polymeric latex component, rather than as a separatelyadded component.

In an embodiment, the stabilizer may be present in an amount of about 0to about 10 phr, such as about 1 to about 6 phr, or about 2 to about 4phr. In an embodiment, the stabilizer has a pH of about 5 to about 13,such as about 6 to about 12, or about 7 to about 11 and a solids contentof about 35 to about 85%, such as about 40 to about 80%, or about 45 toabout 75%.

In an embodiment, the composition is substantially or completely free ofcure agents, such as, for example, sulfur or peroxide. Substantiallyfree in this context means that no cure agents are added for the purposeof curing the composition, and are only present for another purpose inthe composition or as accidental contaminants, for example, less than 1phr or less than 0.1 phr. However, in another embodiment, cure agentsmay also be used in conventional quantities. Without being bound bytheory, it is believed that the cure agents and accelerators that leachout of the elastomer substrate that the adhesive is applied to aresufficient to impart a cure to the adhesive under curing conditions. Thepenetrant is believed to aid in leaching sufficient quantities of thecure agent and accelerators from the elastomer substrate.

In an embodiment, the entire adhesive composition will have a pH ofabout 7 to about 14, such as about 8 to about 13, or about 9 to about12, and a solids content of about 25 to about 75%, such as, about 30% toabout 70%, or about 35 to about 65%. Furthermore, in an embodiment, theadhesive will be substantially or completely free of VOCs. A volatileorganic compound (VOC) is any carbon-based compound that will vaporizeat standard room temperatures. There are many organic compounds thatfall into this category, with methane, formaldehyde and acetone amongthe most prevalent and well-known VOCs. These compounds are producedthrough natural biological processes as well as through chemicalreactions in manufacturing and industry. Whether a composition is freeor substantially free of VOCs is based upon its vapor pressure.

In an embodiment of the method of making of the adhesive the componentslisted above are mixed together at ambient temperature. Namely, thepolymeric latex, the penetrant, the reinforcing filler, the tackifier,and the stabilizer are mixed together. In another embodiment, either thepenetrant or the stabilizer or both may be omitted.

The components may be added sequentially or simultaneously, in the orderthey are listed above or in a different order. For example, thecomponents may be sequentially added and allowed to slowly rotate in aclosed vessel long enough to ensure mixing and good dispersion, such asat least 24 hours.

While the mixing conditions and order of component addition may bevaried, care should be taken to maintain the composition in the latexemulsion phase. In this regard, maintaining a solids content of 35-65%and a pH of 9 to 12 throughout the steps of the method is preferred.

The adhesive composition thus formed may be applied to a substrate suchas a cured or an uncured rubber composition by, for example, rolling,spraying, or extruding it onto the substrate. After application to anuncured rubber substrate the adhesive and the uncured composition may bethen cured under conditions necessary for the substrate to cure. Withoutbeing bound by theory, the cure agent and accelerators in the substrateare believed to leach into the adhesive in a sufficient quantity tocause the adhesive to cure also.

The substrates that the adhesive may be utilized to join includeelastomeric rubber substrates such as rubber compositions that have asthe polymeric component polychloroprene, butyl rubber, hevea andnon-hevea natural rubber, polyisoprene, polybutadiene, nitrile rubber,poly(isoprene-styrene), poly(isoprene-butadiene),poly(styrene-butadiene), and combinations thereof. The adhesive may alsohave some utility for bonding metals, wood, and other types ofsubstrates.

FIG. 1 shows an embodiment of a reversible sleeve air spring 10 In FIG.1, the air spring assembly 10 includes flexible airsleeve 12. Bead plate14 is crimped to airsleeve 12 to form an airtight seal between the beadplate 14 and airsleeve 12. Similarly, end closure 16 is molded to theflexible airsleeve 12 to form an airtight seal between end closure 16and airsleeve 12. End closure 16 of airsleeve 12 is affixed to piston 18by mechanical means well known in the art, including, for example, apiston bolt (not shown). Piston 18 provides a surface for the flexibleairsleeve 12 to roll on during compressive travel. The reversible airspring assembly 10 may optionally include a bumper 20 to support thevehicle when there is no air in the air springs or during extreme roaddisturbances. Enclosed within airsleeve 12 is a volume of gas 22. Studs24 and hole 26 are used to secure the reversible air spring assembly 10to the mounting surface of an automobile (not shown).

In one example, the application adhesive is applied between rubberlayers for air-springs to securely join them at an interface. Withinsuch rubber layers it may contain fibers and/or woven-fabric forreinforcement.

Air springs are widely used in large vehicles, such as buses and trucks,because they allow fixedly holding a vehicle's posture against a loadchange from curb weight to payload weight by controlling the supply ofair and the discharge of air to the exterior. In addition, the springconstant can be set to a low level to improve the ride comfort andprevent the damage of freight.

Typical air spring rubber compositions include one or more dienepolymers, such as polychloroprene; a reinforcing filler, such as carbonblack, in an amount such as 20-100 phr; a cure agent, accelerators, wax,plasticizing oil, antioxidants, and other additives. An example airspring composition is disclosed in WO 2010/019862, which is incorporatedherein by reference.

FIG. 2 shows a cross-section of a tire 100. In an example applicationthe adhesive is applied to various rubber components of the tire 100including, but not limited to, new tire construction or existing tireretreading. For instance, the adhesive may be applied to join a splicedtread 110, a spliced inner liner 120, or a spliced bead 130, or to joina sidewall 140 or a carcass layer 150 to the tread 110.

In tire retreading, the cured tread and the cured tire carcass arejoined together by combining a cushion layer. The retreaded tire is thenheated in a standard set of conditions to allow for curing to occur. Informing a retreaded tire 300, the adhesive may be applied to join acushion layer 302 to a retreaded carcass 306 or a cushion layer to a newtread 304, as shown in FIG. 3. An example of a retread tire and a methodfor retreading is disclosed in U.S. Pat. No. 5,603,366, which isincorporated herein by reference.

Typical tire rubber compositions include one or more diene polymers,reinforcing filler, such as carbon black, in an amount such as 40-100phr, sulfur (cure agent), accelerators, plasticizing oil, antioxidants,and other additives.

New tires are constructed by assembling the individual components in anuncured (green) state, and then, once assembled, the green tire is curedas a whole. An example tire manufacturing method is disclosed in U.S.Pat. No. 4,824,501, which is incorporated herein by reference.

As the Examples below show, the adhesive described herein is well-suitedfor use in the manufacture of rubber articles such as tires and airsprings.

EXAMPLES Examples 1 and 2

The example adhesives were prepared by sequentially mixing thecomponents listed in Table 1 and allowing them to slowly rotate in aclosed vessel for at least 24 hours to ensure mixing and gooddispersion. The final example adhesives had solids contents in the rangeof 35-65% and a pH in the range of 9-12.

TABLE 1 Component Amount EXAMPLE 1 Neoprene Latex 100 phr Limonene 5 phrTACOLYN 5003 25 phr AQUABLAK 5101 25 phr EXAMPLE 2 Neoprene Latex 100phr Limonene 5 phr AQUATAC 6025 25 phr AQUABLAK 5101 25 phr

Examples 3-18

Examples 3-10 were performed to test the tackiness and thestrength/durability of the Example 1 and 2 adhesives in comparison toother adhesives and against a stock to stock control when applied to aneoprene rubber composition. Neoprene rubber is commonly used in airsprings.

Examples 3-6 were prepared to measure the uncured (green) peel strength.This measurement primarily shows the tackiness of the joint. Thisindicates an initial adhesiveness to hold a joint together temporarilyuntil it can be cured.

Examples 7-10 were prepared to measure the cured peel strength, whichshows the strength and durability of the final cured joint.

The application of the adhesive onto the green rubber stock was donewith a foam/sponge brush, in order to get a thin uniform layer ofapplication. The adhesive was allowed to dry at room temperature for onehour before the uncured samples were tested, and before the curedsamples were cured by heating at 171° C. for 11.5 min.

In Examples 3 and 7 no adhesive was applied. In Example 3, two uncuredneoprene stocks were applied together in an uncured state. In Example 7the neoprene stocks were applied together uncured and then later cured.This provides a very strong bond, because the same material is beingcontacted and cured together. The joint is only slightly weaker than anunjointed piece of rubber, partly because some contaminants may bloom tothe surface of the joint and contaminate the curing at the joint.Accordingly, these Examples are considered control examples, notcomparative Examples.

Examples 4 and 8 were neoprene rubber strips joined with a hexanesolvent-based adhesive made from natural rubber and styrene-butadienerubber.

Examples 5, 6, 9, and 10 employed the adhesives made in Examples 1 and2.

Examples 11-18 are analogs to Examples 3-10, only differing in that adifferent Neoprene rubber was used. The Neoprene rubbers 1 and 2 werecopolymers of chloroprene and 2,3-dichloro-1,3-butadiene. Neoprenerubber 1 had a Mooney viscosity of about 100-120, and neoprene rubber 2had a Mooney viscosity of about 41-51.

The peel strength test strength Examples are summarized in Tables 2 and3.

TABLE 2 Compounded Air Spring 180° Peel Results: Avg. Rubber StockAdhesive Peel Strength (MPa) Example 3 Neoprene rubber Stock-to- 0.0416(Control) 1 no cure (green) Stock (none) Example 4 Neoprene rubberSolvent 0.0333 (Compar- 1 no cure (green) Adhesive ative) Example 5Neoprene rubber Example 1 0.0380 1 no cure (green) Example 6 Neoprenerubber Example 2 0.0447 1 no cure (green) Example 7 Neoprene rubberStock-to- 0.2244 (Control) 1 Cured Stock (none) Example 8 Neoprenerubber Solvent 0.0435 (Compar- 1 Cured Adhesive ative) Example 9Neoprene rubber Example 1 0.3125 1 Cured Example 10 Neoprene rubberExample 2 0.2976 1 Cured

TABLE 3 Compounded Air Spring 180° Peel Results: Avg. Rubber StockAdhesive Peel Strength (MPa) Example 11 Neoprene rubber Stock-to- 0.0530(Control) 2 no cure (green) Stock (none) Example 12 Neoprene rubberSolvent 0.0400 (Compar- 2 no cure (green) Adhesive ative) Example 13Neoprene rubber Example 1 0.710 2 no cure (green) Example 14 Neoprenerubber Example 2 0.0550 2 no cure (green) Example 15 Neoprene rubberStock-to- 0.3231 (Control) 2 cured Stock Example 16 Neoprene rubberSolvent 0.0184 (Compar- 2 cured Adhesive ative) Example 17 Neoprenerubber Example 1 0.2367 2 cured Example 18 Neoprene rubber Example 20.3520 2 cured

In the construction of the uncured adhesion pads that were used in thetack testing of Examples 3-6, the backing pad was secured to the greenrubber neoprene stock using superglue (cyanoacrylate). For the curedadhesion pads that were used in Examples 7-10 to determine the strengthand durability of the adhesive bond, the backing pad was cured onto therubber stock without superglue.

In Examples 3-10, the green rubber stock and the backing pad wereweighed before any adhesive was applied. For the adhesive application, afoam/sponge brush was used to apply the adhesive in a thin, uniformlayer onto each face of the adhesion pad. It was observed that all ofthe adhesives coated and wetted the rubber well. The pads were weighedagain after the adhesive had been applied and dried at room temperaturefor at least an hour in order to get the weight of the adhesive. Theweights of adhesive in each Example were approximately the same. InExamples 7-10, after the pads were assembled, the samples were cured at171° C. for 11.5-min.

A standard procedure for 180° peel testing on an Instron 4501 was usedfor all of the Examples 3-10. These Examples were peel tested at a rateof 2 in/min and the gap distance was 127 mm. The cured Examples 15-18were aged for 5 days before testing. This same test was performed forboth uncured (Examples 3-6, 11-14) and cured adhesion (Examples 7-10,15-18).

Shown in Table 2 are the uncured and cured results for the 180° peeltest for Examples 3-10, respectively. Shown in Table 3 are the uncuredand cured results for the 180° peel test for Examples 11-18,respectively. In each Figure the higher the average peel strengthindicates the better the adhesive performance.

Table 2 and 3 show the uncured tack comparison and the cured adhesivestrength comparison. The Example 1 and 2 adhesive formulationsdemonstrate versatility on different types of air spring rubber, and ineither the uncured or cured state. In addition, the water-basedadhesives of Examples 1 and 2 reduce the VOC emissions released upondrying in comparison to a traditional solvent-based adhesive.

Example 19

The Example 19 adhesive was prepared by sequentially mixing thecomponents listed in Table 4 and allowing them to slowly rotate in aclosed vessel for at least 24 hours to ensure mixing and gooddispersion. The final adhesive had a solids content in the range of35-65% and a pH in the range of 9-12.

TABLE 4 EXAMPLE 19 Component Amount Natural Rubber Latex 100 phr IGEPALCO-887 1 phr Limonene 10 phr TACOLYN 5070 25 phr AQUABLAK 5101 25 phr

Examples 20-25

Examples 20-25 were performed to test the tackiness and thestrength/durability of the Example 19 adhesive in comparison to otheradhesives and against a stock to stock control when applied to a typicalstyrene-butadiene and natural rubber blend tire compound that alsoincluded carbon and silica, sulfur, and accelerators.

Examples 20-22 were prepared to measure the uncured (green) peelstrength, which primarily shows the tackiness of the joint. Thisindicates an initial adhesiveness to hold a joint together temporarilyuntil it can cure.

Examples 23-25 were prepared to measure the cured peel strength, whichshows the strength and durability of the final cured joint.

The application of the adhesive onto the green SBR/NR stock was donewith a foam/sponge brush, in order to get a thin uniform layer ofapplication. The adhesive was allowed to dry at room temperature for onehour before the uncured samples were tested, and before the curedsamples were cured by heating at 171° C. for 15 min. The amount ofadhesive was approximately equal in all Examples.

In Examples 20 and 23 no adhesive was applied. In Example 20, twouncured SBR/NR stocks were applied together in an uncured state, inExample 23 the stocks were applied together uncured and then cured.

Examples 21 and 24 were SBR/NR strips joined with a hexane solvent-basedadhesive made from natural rubber and styrene-butadiene rubber.

Examples 22 and 25 employed the adhesive made in Example 19.

TABLE 5 Compounded Air Spring 180° Peel Results: Avg. Rubber StockAdhesive Peel Strength (MPa) Example 20 Natural Rubber Stock-to- 0.0012(Control) no cure (green) Stock (None) Example 21 Natural Rubber Solvent0.0664 (Compar- no cure (green) Adhesive ative) Example 22 NaturalRubber Example 19 0.0702 no cure (green) Example 23 Natural RubberStock-to- 0.3861 (Control) cured Stock (none) Example 24 Natural RubberSolvent 0.2133 (Compar- cured Adhesive ative) Example 25 Natural RubberExample 19 0.2326 Cured

The same test method was performed on Examples 20-25 that was performedon Examples 3-18.

Shown in Table 5 are the uncured and then cured results for the 180°peel test for Examples 20-25, respectively. In Table 5 the higher theaverage peel strength indicates the better adhesive performance.

Table 5 also shows the uncured tack comparison of Examples 20-22 and thecured adhesive strength comparison of Examples 23-25. The Example 19adhesive formulation tested in Examples 22 and 25 demonstrates excellentperformance on SBR/NR in either the cured or uncured state. In addition,the water-based adhesive of Example 19 reduces the VOC emissionsreleased upon drying in comparison to the traditional solvent-basedadhesive.

Prospective Examples 26-28

Prospective example adhesives incorporating guayule resin may beprepared by sequentially mixing the components listed in Table 6 andallowing them to slowly rotate in a closed vessel to ensure mixing andgood dispersion.

In Prospective Examples 26 and 27 a guayule resin may be incorporated asthe penetrant.

In Prospective Example 27, a purified form of guayule rubber latex maybe used as the latex component of the adhesive.

In Prospective Example 28 guayule latex may be used that includes boththe guayule rubber and guayule resin.

The final products in each of Prospective Examples 26-28 would beexpected to have a solids content in the range of 35-65% and a pH in therange of 9-12.

TABLE 6 Component Amount EXAMPLE 26 (Prospective) Natural Rubber Latex100 phr Guayule Resin 5 phr TACOLYN 5003 25 phr AQUABLAK 5101 25 phrEXAMPLE 27 (Prospective) Guayule Rubber Latex (purified) 100 phr GuayuleResin 5 phr AQUATAC 6025 25 phr AQUABLAK 5101 25 phr EXAMPLE 28(Prospective) Guayule Latex (including 105 phr guayule rubber andguayule resin) AQUATAC 6025 25 phr AQUABLAK 5101 25 phrIt is expected that the prospective water-based adhesive formulationsabove will have reduced VOC emissions and improved tack and curedadhesion. In particular, these advantages may be useful in tire buildingapplications.

Examples 29-32

The adhesives in Examples 29 and 30 were prepared by sequentially mixingthe components listed in Table 7 and allowing them to slowly rotate in aclosed vessel to ensure mixing and good dispersion. The final adhesiveshad a solids content in the range of 50-60% and a pH in the range of9.5-11.5. The guayule latex used in Example 30 was in a purified formthat included only guayule rubber with little or no guayule resinpresent.

TABLE 7 EXAMPLES 29 30 HARTEX 101 100 phr (FIRESTONE RUBBER) GuayuleRubber Latex 100 phr (purified) (YULEX CORP.) IGEPAL CO-887 1 phr 1 phrLimonene 10 phr 10 phr TACOLYN 5070 25 phr 25 phr AQUABLAK 5101 25 phr25 phr

Example 31 is a comparative example of a solvent based adhesive. Acomparison of cured and uncured peel strengths is provided below inTable 8. The peel tests were conducted by applying the adhesives ontouncured (green) and cured styrene-butadiene rubber stock atapproximately equal thicknesses. The adhesive was allowed to dry at roomtemperature for one hour before the uncured samples were tested. Thecured samples were prepared by heating the green stocks with theadhesive applied on them at 171° C. for 15 min

TABLE 8 Maximum Uncured Maximum Cured Peel Force Peel Force (kN) ± error(kN) ± error Example HARTEX 101 0.064 ± 15% 0.263 ± 10% 29 AdhesiveExample Guayule Latex 0.058 ± 20% 0.180 ± 20% 30 Adhesive ExampleHexane-based 0.049 ± 18% 0.181 ± 25% 31 adhesive made from NR and SBR

To the extent that the term “includes” or “including” is used in thespecification or the claims, it is intended to be inclusive in a mannersimilar to the term “comprising” as that term is interpreted whenemployed as a transitional word in a claim. Furthermore, to the extentthat the term “or” is employed (e.g., A or B) it is intended to mean “Aor B or both.” When the applicants intend to indicate “only A or B butnot both” then the term “only A or B but not both” will be employed.Thus, use of the term “or” herein is the inclusive, and not theexclusive use. See Bryan A. Garner, A Dictionary of Modern Legal Usage624 (2d. Ed. 1995). Also, to the extent that the terms “in” or “into”are used in the specification or the claims, it is intended toadditionally mean “on” or “onto.” Furthermore, to the extent the term“connect” is used in the specification or claims, it is intended to meannot only “directly connected to,” but also “indirectly connected to”such as connected through another component or components.

While the present application has been illustrated by the description ofembodiments thereof, and while the embodiments have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. Therefore, the application, in its broaderaspects, is not limited to the specific details, the representativeapparatus, and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thespirit or scope of the applicant's general inventive concept.

1-20. (canceled)
 21. An adhesive comprising: a polymeric latex; apenetrant selected from the group consisting of: terpenes, limonene,polylimonene, carvone, α-pinene, citral, dipentene, 1,8-cineole,eucalyptol, citronellol, geraniol, citronellene, terpinen-4-ol, borneol,camphor, guayule resin, and combinations thereof; a reinforcing filler;wherein the adhesive has a solids content of 35-65% and a pH of 9 to 12.22. The adhesive of claim 21 wherein the pH of the polymeric latex iswithin the range of about 7 to about
 14. 23. The adhesive of claim 21wherein the solids content of the polymeric latex is in the range ofabout 10% to about 90% by weight.
 24. The adhesive of claim 21 whereinthe reinforcing filler is carbon black and is present in an amount of 10to 80 phr.
 25. The adhesive of claim 21 further comprising a tackifierwith a pH of about 2 to about 13 and a solids content of about 30 toabout
 80. 26. The adhesive of claim 21 wherein the reinforcing filler iscarbon black and is selected from the following series: N100, N200,N300, N400, N500, N600, N700, N800, and N900.
 27. The adhesive of claim21 wherein the polymeric latex comprises water and a polymer selectedfrom the group consisting of polychloroprene, butyl rubber, hevea ornon-hevea natural rubber, polyisoprene, polybutadiene, nitrile rubber,poly(styrene-butadiene), and combinations thereof.
 28. The adhesive ofclaim 21 wherein the polymeric latex comprises water and a polymerselected from the group consisting of polychloroprene, butyl rubber,hevea or non-hevea natural rubber, polyisoprene, polybutadiene, nitrilerubber, and combinations thereof.
 29. The adhesive of claim 21 furthercomprising a non-ionic surfactant stabilizer.
 30. The adhesive of claim21 wherein the adhesive is substantially or completely free ofVOC-containing or eluting solvent.
 31. The adhesive of claim 21 whereinthe adhesive is substantially or completely free of cure agents.
 32. Theadhesive of claim 21, wherein the penetrant is guayule resin.
 33. Anarticle of manufacture comprising: an elastomeric rubber componentcomprising an elastomer selected from the group consisting of:polychloroprene, butyl rubber, natural rubber, guayule rubber,polyisoprene, polybutadiene, nitrile rubber, poly(styrene-butadiene),and combinations thereof; the elastomeric rubber component being joinedat an interface with a second rubber component or another portion of theelastomeric rubber component; wherein the interface includes a layer ofadhesive, the adhesive comprising: a polymeric latex; a penetrantselected from the group consisting of: terpenes, polylimonene, limonene,carvone, α-pinene, citral, dipentene, 1,8-cineole, eucalyptol,citronellol, geraniol, citronellene, terpinen-4-ol, borneol, camphor,guayule resin, and combinations thereof; and a reinforcing filler. 34.The article of manufacture of claim 33, wherein the article is a rubberair spring or a tire component.
 35. The article of manufacture of claim33, wherein the adhesive has a solids content of 35-65% and a pH of 9 to12.
 36. A method comprising the steps of: mixing together an adhesivecomposition comprising: a polymeric latex; a penetrant selected from thegroup consisting of: terpenes, polylimonene, limonene, carvone,α-pinene, citral, dipentene, 1,8-cineole, eucalyptol, citronellol,geraniol, citronellene, terpinen-4-ol, borneol, camphor, guayule resin,and combinations thereof; and a reinforcing filler.
 37. The method ofclaim 36 wherein the reinforcing filler is added as an aqueousdispersion.
 38. The method of claim 36 further comprising: maintaining asolids content of 35-65% and a pH of 9 to 12 in the compositionthroughout the steps.
 39. The method of claim 36, further comprising thestep of applying the adhesive to an uncured rubber composition.
 40. Themethod of claim 36, further comprising applying the adhesive to a tirecomponent or an air spring joint interface.